I've been experiencing a weird issue where apps (Firefox, Dropbox, SABnzbd, foobar2000, VLC, Media Player Classic etc) won't appear/aren't accessible.
Internet Explorer: After clicking on the icon in taskbar for Firefox/etc, the icon will be active (has an outline) briefly before the border disappears. Then, nothing... It's as though I never did anything. I check Task Manager, and see the Process is listed but the memory is ~100 K only. Killing the process doesn't fix things for me -- the behavior keeps happening until I reboot.
I've re-installed Windows 7 Pro 64-bit; it's fully patched. Grabbed AVG Free -- nothing turns up in a scan. Seems to be if I start an app immediately after startup/login, things go OK but eventually I encounter this behavior with some app.
I'd Google, but I can't think/find a worthy description...